Emily LakdawallaNov 03, 2016

Juno update: 53.5-day orbits for the foreseeable future, more Marble Movie

Juno suffered two setbacks in October. First, a problem with check valves in the main thruster system prevented a planned rocket burn during its October 19 close pass by Jupiter. The science team raced to use the burnless perijove pass to do some science, but then the spacecraft went into safe mode on October 19, before perijove, and before the science sequences could kick in. Juno exited safe mode on October 24 and performed a half-hour burn with its maneuvering thrusters -- not its main thrusters, which were still not being used, pending the outcome of the investigation into the check valve problem. An article at Spaceflight Now goes into much more detail about the investigation into both engine problem and safing event.

At the DPS/EPSC meeting last week, principal investigator Scott Bolton spoke about keeping Juno in its long, 53.5-day orbit for a long time, not ruling out the possibility of performing the entire mission in such an orbit. Juno only gets exposed to dangerous radiation when very close to Jupiter, so the spacecraft wouldn't be exposed to any additional radiation by doing this, though it would seriously prolong the mission. If the mission has not ended by September 2019, Jupiter will have traveled far enough around the Sun that Juno will pass into Jupiter's shadow for several hours on every orbit, a condition that it was not designed for and which could harm its power system; the mission would need to develop a solution to that problem.

At present, the future orbital path of Juno is still uncertain. For the time being, it will stay in its 53.5-day orbit. According to JunoCam team member Glenn Orton, the next planned perijoves in that orbit would be:

PerijoveDate/time (UTC, SCET)longitude of equator
crossing (System III)
PJ22016 Oct 19 18:12:01348.83 deg W
PJ32016 Dec 11 17:05:087.03 deg W
PJ42017 Feb 2 12:59:12277.00 deg W
PJ52017 Mar 27 08:53:20187.00 deg W
PJ62017 May 19 06:01:51142.00 deg W
PJ72017 Jul 11 01:55:5652.00 deg W
PJ82017 Sep 1 21:50:01322.00 deg W
PJ92017 Oct 24 17:44:04232.00 deg W
PJ102017 Dec 16 17:58:48299.50 deg W
PJ112018 Feb 7 13:53:23209.50 deg W
PJ122018 Apr 1 09:47:24119.50 deg W
PJ132018 May 24 05:41:2529.50 deg W
PJ142018 Jul 16 05:18:4474.50 deg W
PJ152018 Sep 7 01:13:46344.50 deg W
PJ162018 Oct 29 21:07:49254.50 deg W
PJ172018 Dec 21 17:01:52164.50 deg W
PJ182019 Feb 12 17:36:13243.25 deg W
PJ192019 Apr 6 13:30:13153.25 deg W
PJ202019 May 29 09:24:1863.25 deg W
PJ212019 Jul 21 05:18:43333.25 deg W
PJ222019 Sep 11 20:14:4361.87 deg W

At any perijove, of course, they could decide to go ahead and shift Juno to a shorter orbit with a main engine burn -- we'll just have to wait and see.

In the meantime, JunoCam imaging scientist Candy Hansen told me that the camera has not been turned on since the sticky-valve problem reared its head, and will not be turned on until perijove 3, on December 11. I've now updated my Marble Movie index page with all the JunoCam images received on Earth to date. Below is the near-final version of the JunoCam Marble Movie, covering July 10 through October 14, 2016, between perijoves 0 and 2; all that is missing is the extra-close frames of perijove 1.

JunoCam's "Marble Movie," July 10-October 14, 2016 (near-final version) This movie is assembled from processed JunoCam images. It covers the whole, initially scheduled Marble Movie Phase from after perijove 0 (July 4, 2016) to before perijove 2 (October 19). There are two 7-hour gaps when JunoCam didn't take images before perijove 1 (August 27), and a weeklong gap during solar conjunction (September 23-29). The perijove 1 flyby itself is also not included; it requires special processing, which is ongoing. NASA / JPL / SwRI / MSSS / Gerald Eichstaedt

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